140 research outputs found
Pilot-scale crossflow-microfiltration and pasteurization to remove spores of Bacillus anthracis (Sterne) from milk
High-temperature, short-time pasteurization of milk
is ineffective against spore-forming bacteria such as
Bacillus anthracis (BA), but is lethal to its vegetative
cells. Crossflow microfiltration (MF) using ceramic
membranes with a pore size of 1.4 μm has been shown
to reject most microorganisms from skim milk; and,
in combination with pasteurization, has been shown to
extend its shelf life. The objectives of this study were
to evaluate MF for its efficiency in removing spores
of the attenuated Sterne strain of BA from milk; to
evaluate the combined efficiency of MF using a 0.8-μm
ceramic membrane, followed by pasteurization (72°C,
18.6 s); and to monitor any residual BA in the permeates
when stored at temperatures of 4, 10, and 25°C
for up to 28 d. In each trial, 95 L of raw skim milk
was inoculated with about 6.5 log10 BA spores/mL of
milk. It was then microfiltered in total recycle mode
at 50°C using ceramic membranes with pore sizes of
either 0.8 μm or 1.4 μm, at crossflow velocity of 6.2 m/s
and transmembrane pressure of 127.6 kPa, conditions
selected to exploit the selectivity of the membrane.
Microfiltration using the 0.8-μm membrane removed
5.91 ± 0.05 log10 BA spores/mL of milk and the 1.4-
μm membrane removed 4.50 ± 0.35 log10 BA spores/
mL of milk. The 0.8-μm membrane showed efficient
removal of the native microflora and both membranes
showed near complete transmission of the casein proteins.
Spore germination was evident in the permeates
obtained at 10, 30, and 120 min of MF time (0.8-μm
membrane) but when stored at 4 or 10°C, spore levels
were decreased to below detection levels (≤0.3 log10
spores/mL) by d 7 or 3 of storage, respectively. Permeates
stored at 25°C showed coagulation and were
not evaluated further. Pasteurization of the permeate
samples immediately after MF resulted in additional
spore germination that was related to the length of
MF time. Pasteurized permeates obtained at 10 min of
MF and stored at 4 or 10°C showed no growth of BA
by d 7 and 3, respectively. Pasteurization of permeates
obtained at 30 and 120 min of MF resulted in spore
germination of up to 2.42 log10 BA spores/mL. Spore
levels decreased over the length of the storage period
at 4 or 10°C for the samples obtained at 30 min of MF
but not for the samples obtained at 120 min of MF.
This study confirms that MF using a 0.8-μm membrane
before high-temperature, short-time pasteurization
may improve the safety and quality of the fluid milk
supply; however, the duration of MF should be limited
to prevent spore germination following pasteurization
Effect of guar gum on the physicochemical, thermal, rheological and textural properties of green edam cheese
In attempts to produce a low-fat cheese with a rheology and texture similar to that of a full-fat cheese, guar gum (within 0.0025–0.01%; w/v, final concentration) was added to low-fat milk. The obtained cheeses were characterised regarding their physicochemical, thermal, rheological and textural properties. Control cheeses were also produced with low and full-fat milk. The physicochemical properties of the guar gum modified cheeses were similar to those of the low-fat control. No significant differences were detected in the thermal properties (concerning the enthalpy and profile of water desorption) among all types of cheeses. The rheological behaviour of the 0.0025% modified cheese was very similar to the full-fat control. Overall, no trend was observed in the texture profile (hardness, cohesiveness, gumminess and elasticity) of the modified cheeses versus guar gum concentration, as well as in comparison with the control groups, suggesting that none of the studied polysaccharide concentrations simulated the textural functions of fat in Edam cheese
Differential scanning calorimetric analysis of edible oils: comparison of thermal properties and chemical composition
The thermal profiles of 17 edible oil samples from different plant origins were examined by differential scanning calorimetry (DSC). Two other confirmatory analytical techniques, namely gas-liquid chromatography (GLC) and high-performance liquid chromatography (HPLC), were used to determine fatty acid (FA) and triacylglycerol (TAG) compositions. The FA and TAG compositions were used to complement the DSC data. Iodine value (IV) analysis was carried out to measure the degree of unsaturation in these oil samples. The DSC melting and crystallization curves of the oil samples are reported. The contrasting DSC thermal curves provide a way of distinguishing among these oil samples. Generally, the oil samples with a high degree of saturation (IV65). Each thermal curve was used to determine three DSC parameters, namely, onset temperature (T o ), offset temperature (T f ) and temperature range (difference between T o and T f ). Reproducibility of DSC curves was evaluated based on these parameters. Satisfactory reproducibility was achieved for quantitation of these DSC parameters. The results show that T o of the crystallization curve and T f of the melting curve differed significantly (P<0.01) in all oil samples. Our observations strengthen the premise that DSC is an efficient and accurate method for characterizing edible oils
What is the value and impact of quality and safety teams? A scoping review
<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to conduct a scoping review of the literature about the establishment and impact of quality and safety team initiatives in acute care.</p> <p>Methods</p> <p>Studies were identified through electronic searches of Medline, Embase, CINAHL, PsycINFO, ABI Inform, Cochrane databases. Grey literature and bibliographies were also searched. Qualitative or quantitative studies that occurred in acute care, describing how quality and safety teams were established or implemented, the impact of teams, or the barriers and/or facilitators of teams were included. Two reviewers independently extracted data on study design, sample, interventions, and outcomes. Quality assessment of full text articles was done independently by two reviewers. Studies were categorized according to dimensions of quality.</p> <p>Results</p> <p>Of 6,674 articles identified, 99 were included in the study. The heterogeneity of studies and results reported precluded quantitative data analyses. Findings revealed limited information about attributes of successful and unsuccessful team initiatives, barriers and facilitators to team initiatives, unique or combined contribution of selected interventions, or how to effectively establish these teams.</p> <p>Conclusions</p> <p>Not unlike systematic reviews of quality improvement collaboratives, this broad review revealed that while teams reported a number of positive results, there are many methodological issues. This study is unique in utilizing traditional quality assessment and more novel methods of quality assessment and reporting of results (SQUIRE) to appraise studies. Rigorous design, evaluation, and reporting of quality and safety team initiatives are required.</p
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